2D arrays using NSMutableArray

Question

I need to create a mutable two-dimensional array in Objective-C.

For example I have:

NSMutableArray *sections;
NSMutableArray *rows;

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Answer 1

Reviving an old thread, but I reworked Jack's code so 1. it compiles and 2. it is in the order of 2D c arrays [rows][columns] instead of [sections(columns)][rows] as he has it. Here you go!

TwoDArray.h:

#import 

@interface TwoDArray : NSObject

@property NSMutableArray *rows;

- initWithRows:(NSUInteger)rows columns:(NSUInteger)columns;
+ sectionArrayWithRows:(NSUInteger)rows columns:(NSUInteger)columns;
- objectInRow:(NSUInteger)row column:(NSUInteger)column;
- (void)setObject:(id)obj inRow:(NSUInteger)row column:(NSUInteger)column;

@end

TwoDArray.m:

#import "TwoDArray.h"

@implementation TwoDArray

- (id)initWithRows:(NSUInteger)rows columns:(NSUInteger)columns {
    if ((self = [self init])) {
        self.rows = [[NSMutableArray alloc] initWithCapacity: rows];
        for (int i = 0; i < rows; i++) {
            NSMutableArray *column = [NSMutableArray arrayWithCapacity:columns];
            for (int j = 0; j < columns; j++) {
                [column setObject:[NSNull null] atIndexedSubscript:j];
            }
            [self.rows addObject:column];
        }
    }
    return self;
}
+ (id)sectionArrayWithRows:(NSUInteger)rows columns:(NSUInteger)columns {
    return [[self alloc] initWithRows:rows columns:columns];
}
- (id)objectInRow:(NSUInteger)row column:(NSUInteger)column {
    return [[self.rows objectAtIndex:row] objectAtIndex:column];
}
- (void)setObject:(id)obj inRow:(NSUInteger)row column:(NSUInteger)column {
    [[self.rows objectAtIndex:row] replaceObjectAtIndex:column withObject:obj];
}
@end